This Valentine's Day, millions of people will exchange heart-shaped gifts of all kinds, from candy to cards. But did you know that the human heart does not actually look like the typical valentine shape?

National Geographic Kids spoke with heart specialist Robert DiBianco to learn more about this important organ.

According to Dr. DiBianco, the human heart is about the size of a fist.

"Because [the heart] is a muscle with lots of blood supplied to it, it looks red like meat," he explained. "In people who are overweight . . . the heart looks yellow because it is covered with yellow fat."

In the United States children are taught to place their hands over their hearts when pledging allegiance to the flag. Most people have heard that the heart is on the left side of the chest. In reality, the heart is in the middle of the chest, tucked snugly between the two lungs.

But what does the heart actually do?

DiBianco explained that the heart is a pump that pushes blood throughout the body. The heart moves blood by expanding and contracting (getting bigger and smaller).

"Each living part of the body needs blood to live, and that's why it's important for the blood to go to different parts of the body," DiBianco said.

When you're exercising, it takes your blood about ten seconds to get from your heart to your big toe and back. In fact, a kid's heart has to push blood through about 60,000 miles (96,560 kilometers) of blood vessels—that's long enough to circle the Earth two and a half times!

All that pumping takes a lot of effort. To push blood, an average heart beats a hundred thousand times a day. That means that in a lifetime, the average human heart will beat more than two and a half billion times.

Because the heart is so important, the American Heart Association reminds people that they need to treat their hearts with care. Exercise and healthful foods can help the heart do its job.

This Valentine's Day, heart-shaped gifts will be everywhere. Maybe that's why February is also American Heart Month!